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Subject: Re: [PATCH][v2] uio: Support 36-bit physical addresses on 32-bit
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From: Kumar Gala <galak@kernel.crashing.org>
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Date: Thu, 13 Oct 2011 10:32:51 -0500
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To: Tabi Timur-B04825 <B04825@freescale.com>
Cc: "linuxppc-dev@ozlabs.org" <linuxppc-dev@ozlabs.org>,
 "hjk@hansjkoch.de" <hjk@hansjkoch.de>, "gregkh@suse.de" <gregkh@suse.de>,
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 Jiang Kai-B18973 <B18973@freescale.com>
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On Oct 13, 2011, at 9:37 AM, Tabi Timur-B04825 wrote:

> On Wed, Oct 12, 2011 at 3:57 PM, Kumar Gala =
<galak@kernel.crashing.org> wrote:
>> From: Kai Jiang <Kai.Jiang@freescale.com>
>>=20
>> To support >32-bit physical addresses for UIO_MEM_PHYS type we need =
to
>> extend the width of 'addr' in struct uio_mem.  Numerous platforms =
like
>> embedded PPC, ARM, and X86 have support for systems with larger =
physical
>> address than logical.
>>=20
>> Since 'addr' may contain a physical, logical, or virtual address the
>> easiest solution is to just change the type to 'unsigned long long'
>> regardless of which type is utilized.
>=20
> You forgot to update this description.

will fix and update commit message

>=20
>>  struct uio_mem {
>>        const char              *name;
>> -       unsigned long           addr;
>> +       phys_addr_t             addr;
>=20
> Please add a comment here saying:
>=20
> 1) That 'addr' can be a virtual or physical address

The code and everything else makes that clear

> 2) That the kernel guarantees that sizeof(phys_addr_t) >=3D =
sizeof(void
> *), so it's safe to use phys_addr_t for a virtual pointer.

The commit message will cover that so I don't plan on add it.

- k=